Multi-cavity radiant burner

ABSTRACT

A fluid-fueled radiant burner having multiple cavities each individually controlled so that selective high, medium and low heat may be achieved, making the burner suitable for use in a cooking range particularly of the flush top type.

United States Patent [191 v [in 3,843,313 Helgeson Oct. 22, 1974 MULTI-CAVITY RADIANT BURNER 3,468,298 9/1969 Teague et al. 431/328 x l9 l 26 391 [75] inventor: Peter L. llelgeson, Macungie, Pa. 3 606 612 9/ 7 Reld I [73] Assignee: Raytheon Company, Lexington,

Mass. Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-Harold A. Murphy; Joseph [22] Med: 1974 D. Pannone; John T. Meaney [21] Appl. No.: 456,708

Related US. Application Data [63] Continuation of Ser. No. 382.092, July 23, 1973, [57] ABSTRACT abandoned.

g A fluid-fueled radiant burner having multiple cavities 39 J, 431/284 each individually controlled so that selective high, me- Cldium and low heat may be achieved making the [58] Field M Search 431/326 328, 284; burner suitable for use in a cooking range particularly 126/39 R J of the flush top type.

[56] References Cited i 4 Cl 9 D F UNITED STATES PATENTS rawmg 2257399 9/l94l Parker 126/391 60 6 4 45 g y a 62 54 i9 40 32- a 86 .V a

PATENTEUHBTZZ 1914 Q "3.843313 am ans 5 MULTI-CAVITY RADIANT BURNER CROSS-REFERENCE TO RELATED CASES This is a continuation of application Ser. No. 382,092, filed'July 23, 1973, now abandoned.

BACKGROUND OF THE INVENTION I Radiant burners comprise a structure. in which a fluid fuel, such as gas, is burned on the surface of a screen or other porous member to heat the screen to incandescence. Such burners have found common usage as broiler or bake burners in the broiler or oven compartment of a gas-burning cooking stove, or in a space heater or the like.

However, radiant burners presently available are able to maintain only a single heat level, while many applications require means for varying the heat from the burner at several levels ranging from low to high.,So called ported or blue flame burners can be easily controlled in this manner by merely regulating the amount of' gas which is supplied to the burner cavity.

In gas cooking ranges it has been an objective to provide flush top" capabilities which requires that a sheet of flat heat transmissive material such as glass or the like be placed over the top burner or burners. Ported blue flame burners are not suitable for such applications because they operate'on the theory that heat may be applied to a utensil by conduction. Therefore, radiant burners appear to solve this problembecause the heat may be conveyed to the utensil by radiation through the cooktop.

However, utilization of radiant top burners has not developed, one primary reason being that radiant burners as presently made do not include means for varying the heat levels.

SUMMARY OF THE INVENTION The above and other objections are overcome by the present invention wherein'a radiant burner is provided with means for regulating heat to selected levels from low to high, thus rendering such burners suitable as top burners for flushtop and other cooking ranges.

This is achieved by providing the burner with multiple burner cavities, preferably concentric, and with means whereby the burners may be progressively ignited, whereby multi-level heating is achieved. More specifically, a burner is provided with a central cavity of relatively small size, with at least one annular cavity encircling the central cavity. A third cavity, also annular in shape, preferably is provided in encircling relation to the first annular cavity. A single control valve is provided which supplies gas progressively first to the central cavity to provide low heat, then to the first annular cavity'which when ignited will function to supplement the central cavity to provide medium heat, and then to the third cavity which will supplement the first two mentioned cavities to provide high heat.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objectives of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein: y

FIG. 1 is a fragmentary isometric view of a cooking range illustrating a cooktop with burners embodying this invention;

FIG. 2.is a horizontal sectional view through a burner box;

FIG. 3 is an enlarged top plan view of a burner unit embodying the invention;

FIG. 4 is avertical sectional view taken transversely through the burner unit of FIG. 3;

FIG. 5 is a top plan view of a burner unit with combustion screen assembly removed;

FIG. 6 is an isometric view of the burner unit shown in FIG. 5;

FIG. 7 is a top plan view of the range shown in FIG. 1 with a portion of the cooktop removed;

FIG. 8 is an enlarged plan view of the control valve and adjacent piping; and

FIG. 9 is a transverse sectional view through an exemplary distributing valve of a type useful in the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring more particularly to the drawings wherein like characters of reference designate like parts through the several views, in FIG. 1 there is shown a cooking range of the free standing type which includes an upright substantially boxlike body 10 having an oven with a front opening door 12 and, at its upper extremity, a transversely extending cooktop .14. v

The range is intendedto be of the so-called flushtop design and, therefore, is shovm as having a pair of parallel top openings 16. As shown best in FIG. 2, the metal of the cooktop 14 is depressed to form two burner boxes 18 each providedat convenient locations with upstanding supports 20 on which suitably rests a plate 22 of glass or other good infrared transmissive material. The plates 22 are also supported at each corner on bosses 24 provided in the burner boxes and thus are retained at a level substantially in the plane of the cooktop 14. Around its periphery each plate 22 is spaced slightly from the adjacent wall ofthe respective box 18 so as to provide suitable air vents 26.

Within each burner box 18 are positioned a pair of spaced radiant'burner elements 28 which project upwa'rdly through the bottom of the burner boxes 18 (FIG. 2) beneath and spaced from plate 22.

Each burner element 28 is provided on its upper side with three concentric annular walls 30-32-34 as shown best in FIGS. 3-6. Inner wall 30 defines a central cavity 36..Walls 30 and 32 define a substantially annular second cavity 38 therebetween and encircling cavity 36, while walls 32 and 34 define between them a substantially annular third cavity 40 encircling second cavity 38.

Extending into the element 28 through a lower portion of outer wall 34 are three separate conduits 42-4- 4-46, the inner ends of which communicate with the respective cavities 36-38-40. Wall 34 is enlarged or reinforced at 48 and the outer ends of the conduits extend through and terminate at thesurface of wall portion 48. A pipe fitting 50 is mounted as by screws on this outer surface of portion 48 and supports adjacent ends of three pipes 52-54-56 which supply gas to the three respective cavities, as will be described. The bottoms of the annular cavities 38 and 40 are inclined as shown in FIG. 4 to allow conduits 42 and 44 to connect with respective cavities 36 and 38.

Spanning the top of each burner is a combustion sustaining screen assembly which preferably comprises two or more relatively fine mesh metal screens 58 and 60, such as forty mesh, for example. Screens 58 and 60 are superimposed upon one another or slightly spaced apart and are sandwiched asan assembly between inner and outer concentric gaskets 62 and 64 by which the assembly is screwed or similarly attached to the tops of walls 30-32-34. Actually, a third screen (not shown) is preferably utilized in the assembly to prevent flashback, as is known.

Pipes 52-54-56 at their other ends are formed as venturis 66-68-70 respectively (FIG. 7). Adjacent each set of venturis is a valve 72 of the selective distributing type such as shown, for example, in FIG. 8. Pipes or orifices 74-76-78 lead from valve 72 to the associated respective venturis 66-68-70. The valves 72 are operatively connected by rotatable shafts 80 to respective knobs 82 located on a control panel 84 (FIG. 1) near the front edge of cooking top 14. Gas is supplied into the valve 72 via a manifold 73 from any suitable source by means of an inlet pipe 84 and is prevented, when the valve is closed, from passing into pipes 74-7- 6-78 by a cam 79 carried by the shaft 80.

By operation of valve 72, through manipulation of knob 82, the end of pipe 74 will be uncovered by rotation of shaft 80 and cam 79 so that gas will be permitted to flow through the pipe 74 into pipe 52 through venturi 66 where it is mixed with air in the well-known manner. From pipe 52'the gas-air mixture will flow into the conduit 42 and thence into the central cavity 36. This gas-air mixture in cavity 36 may be ignited by any suitable means (not shown) whereupon combustion will take place in the portion 61 of the screen assembly which overlies the cavity 36. This achieves low heat which will radiate upwardly through plate 22 onto a cooking utensil which may be positioned on the plate.

When it it desired to increase the level of heat from the burner it is only necessary that knob 82 be manipulated to rotate shaft 80 and cam 79 to a position where the end of pipe 76 is uncovered. Thus gas is permitted to flow through pipe 76, venturi 68 and pipe 54 into conduit 44, from which it will flow into cavity 38. When the gas-air mixture reaches the portion 63 of the combustion screen assembly which overlies the cavity 38 it will be automatically ignited because of proximity to central cavity 36.

Thus, there is provided an enlarged area of higher level radiant heat wherein both cavities 36 and 38 are operated simultaneously. High level heat may be provided by opening valve 72 still farther to allow gas to flow into the third cavity 40 through pipe 78, venturi 70, pipe 56 and conduit 46, whereupon additional combustion will occur in the portion 65 of the combustion screen assembly which overlies the cavity 40.

Accordingly, it will be apparent from the foregoing that a novel fluid-fueled radiant burner has been achieved in accordance with the objectives of this invention and wherein various heat levels may be achieved in a single burner unit.

It is to be understood, however, that various modifications and changes may be made by those skilled in the art without departing from the spirit of the invention as expressed in the accompanying claims. There fore, all matter shown and described is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A multi-level radiant burner and control system for fluid-fueled ranges comprising a burner head including a chamber having an open side and separated into a plurality of cavities defined by upstanding walls, said cavities including a central cavity and at least one additional cavity encircling the central cavity, a combustion screen assembly mounted over said cavities, and means for attaching the screens to said walls, the bottom of said encircling cavity being inclined upwardly toward said screen, conduits in said head connected separately to the individual cavities therein, and control means for connecting said conduits to a source of fuel, said control means including distributing valve means operable to successively connect said conduits with a source of fuel.

2. A burner and system as set forth in claim 1 wherein said encircling cavity has an end wall located at the end of the conduit which is connected to said encircling cavity, said end wall has a port to provide communication between the conduit and cavity.

3. A burner and system as set forth in claim 2 wherein said conduits lie in a common transverse plane, and the inclined bottom of the encircling cavity at the end thereof opposite the port is disposed above the conduit which is connected to the central cavity.

4. A burner and system as set forth in claim 2 wherein thereare provided two concentric encircling cavities with respective end walls and inclined bottoms, said inclined bottom of the inner of said encircling cavities being disposed above the conduit which is connected to the central cavity, and the inclined bottom of the outer of said encircling cavities being disposed above both the conduits which are connected to the central cavity and the inner encircling cavity. 

1. A multi-level radiant burner and control system for fluidfueled ranges comprising a burner head including a chamber having an open side and separated into a plurality of cavities defined by upstanding walls, said cavities including a central cavity and at least one additional cavity encircling the central cavity, a combustion screen assembly mounted over said cavities, and means for attaching the screens to said walls, the bottom of said encircling cavity being inclined upwardly toward said screen, conduits in said head connected separately to the individual cavities therein, and control means for connecting said conduits to a source of fuel, said control means including distributing valve means operable to successively connect said conduits with a source of fuel.
 2. A burner and system as set forth in claim 1 wherein said encircling cavity has an end wall located at the end of the conduit which is connected to said encircling cavity, said end wall has a port to provide communication between the conduit and cavity.
 3. A burner and system as set forth in claim 2 wherein said conduits lie in a common transverse plane, and the inclined bottom of the encircling cavity at the end thereof opposite the port is disposed above the conduit which is connected to the central cavity.
 4. A burner and system as set forth in claim 2 wherein there are provided two concentric encircling cavities with respective end walls and inclined bottoms, said inclined bottom of the inner of said encircling cavities being disposed above the conduit which is connected to the central cavity, and the inclined bottom Of the outer of said encircling cavities being disposed above both the conduits which are connected to the central cavity and the inner encircling cavity. 